I. Common staging systems for multiple myeloma.
The common staging systems for multiple myeloma are Durie/Salmon staging, ISS international staging and Durie/Salmon plus staging. They are described below.
(i) Durie and Salmon staging.
Durie and Salmon (hereinafter referred to as DS staging) has been used in clinical practice for more than 30 years since 1975. Although its assessment of the degree of bone damage is based on plain X-rays, its clinical application over the years has made it a very reliable staging method and it is still in use today. It provides a practical method for determining the tumor load of multiple myeloma [1]. Huang Zhongxia, Department of Hematology and Oncology, West Hospital, Beijing Chaoyang Hospital, Capital Medical University
In Durie and Salmon staging, tumor load is correlated with individual clinical, laboratory tests, and x-ray features that include hemoglobin, blood calcium and creatinine, serum and urine M protein levels, and the number and size of bone lesions, which determine clinical staging. The use of this staging system allows for a simple and practical assessment of tumor load. Patients are classified as stage I, II or III according to the degree of anemia, hypercalcemia, serum and urinary M-protein levels, and bone damage. In addition, patients were classified into group A or B depending on whether the blood creatinine was ≥2.0 mg/dL. See Table 1.
Table 1 Durie and Salmon staging criteria (1975)
Staging
Staging criteria
Number of tumor cells (×1012/m2 body
surface area)
Stage I
Stage II
Stage III
Each phase was further divided into
Group A and Group B.
Meet the following 4 items.
(1) Hemoglobin >100g/L
(2) Normal serum calcium
(3) No bone destruction
(4) MC component level IgG 5.5mg/dl
Median survival: 29
(iii) Durie/Salmon plus staging system [4].
In the DS staging system, some patients with symptomatic MM who were negative for X-rays and had skeletal examinations with new imaging modalities such as MRI and CT, 20% of patients had bone destruction. Therefore, Durie introduced the Durie/Salmon plus staging system again in 2006 to allow clinicians to stage patients with the help of new imaging examinations. The staging criteria are shown in Table 3.
Table 3 Durie/Salmon plus staging criteria
Durie/Salmon plus staging system
Imaging
Durie/Salmon
Staging
IB
IIA or B
IIIA or B
Plus
MRI/PET
Number of bone damage
I 0-4
II 5-20
III >20
B: Blood creatinine ≥ 2.0 mg/dL
In the above Durie/Salmon plus staging system, Durie performed the following analysis of the advantages and disadvantages of CT, MRI and PET-CT, new imaging modalities in the diagnosis and treatment of myeloma bone disease [2].
Although CT examinations can detect bone destruction in MM patients earlier than X-rays, the skeletal changes detected by CT persist during the course of the disease because the bone destruction does not heal easily during patient treatment.
MRI is particularly helpful for MM patients with combined spinal bone destruction, not only for early detection of bone destruction, but also for spinal cord invasion lesions related to or unrelated to spinal bone destruction. With the exception of early smoldering MM, the number of bone disruptions on MRI is positively correlated with treatment outcome and long-term survival in patients with symptomatic MM. This is consistent with the Durie/Salmon plus staging. However, MRI also takes 9-12 months to predict the efficacy of bone destruction in MM patients; therefore, MRI is not an ideal means of monitoring the efficacy of bone disease.
FDG-PET examination was negative in MGUS and smoldering MM, while symptomatic MM showed positive. FDG-PET shows up hours or days or 3-4 weeks after effective treatment of symptomatic MM and can be used to monitor the efficacy of bone disease and changes in condition. MRI, on the other hand, is delayed by 9-12 hours and is not conducive to disease monitoring. Persistent FDG-PET positivity after several cell transplants is a poor prognostic factor and can predict relapse up to 6 months earlier than bone marrow and M protein.
CT-PET, which combines the advantages of CT and FDG-PET, is an ideal tool for monitoring and predicting the efficacy of bone destruction and disease change in MM.
The advantages of Durie/Salmon plus staging system are as follows.
1. it helps in the early treatment of myeloma bone disease
2 . Helps to differentiate MGUS from smoldering MM
3 .It helps to stage the hypersecretory or nonsecretory type of MM.
4 . Helps to distinguish between stage II and stage III MM.
5 .It helps to identify the subtypes with poor prognosis; such as MRI, CT and other new imaging examinations of the number of bone destruction sites H > 20 with poor prognosis.
Second, the comparison of the three staging systems
The addition of CT, MRI and CT-PET to the DS staging system improved the DS staging system to form the Durie/Salmon plus staging system. Therefore, Durie [4] analyzed and compared the three staging systems (Table 4) and concluded that MM is a heterogeneous disease from the cellular to the clinical level, and no single staging system can ideally cover all MM patients. Patients with hypersecretory or nonsecretory MM with a high tumor load but showing a low serum b2M are not accurately staged using ISS. Some subtypes have low serum b2M early in the course of the disease but have cytogenetic abnormalities such as t(4;14) often with poor prognosis [4].
Table 4 Comparison of different staging criteria
Staging
Durie/Salmon
Staging